R: spherical gnomon

Two years ago, in the X Seminario Nazionale di Gnomonica, (the italian Congress of Gnomonics) I did present a complete research about the spherical gnomon dial, with all types of hours : unequal, astronomical, italic, babylonic. In particular the dial with unequal hours is presented in this work

R: The equinox

This year the Equinox will be on Sep 22 at 17:27 UT. There is a useful link for this kind of data : http://aa.usno.navy.mil/aa/data/docs/EarthSeasons.html Best regards Alberto Nicelli Italy (45°28' N ; 7°52' E) -Messaggio originale- Da: Dave Bell [mailto:[EMAIL PROTECTED] Inviato:

R: Rules of thumb

I find useful this rule of thumb : What is the Sidereal Time at a given time ? S. T. (hours) = time (hours)- 12 + 2 x (number of months from March 21) This is nice to know immediately what constellation passes the meridian at a given time and roughly reproduce the sky using a map ...

R : This says it all I think

I've highly appreciated your contribution Tony : Plato would have been a great dialler Since school-time I remember a Greek sentence (likely said by Plato itself: I don't remember now ...) that would be a perfect motto on our dials ... ... (God is a geometrician ) Alberto Nicelli

R: passing time

Frank Evans wrote : It's suggested by some in our newsgroup that time does not exist. In that case we sundialists are in the wrong business. Time does not exist, that's true, but sundialists have the great privilege of creating it Alberto Nicelli Italy (45* 28' N ; 7 52' E)

Errata corrige

Please correct the oversight in 6) The other axis is perpendicular in V with The other axis is perpendicular in S, described in 7). Alberto -- From: Nicelli Alberto Sent: lunedì 4 maggio 1998 10.35 To: 'Arthur Carlson' Cc: 'sundial@rrz.uni-koeln.de

hyperbola , foci and other more

Hello Arthur . In the last cloudy weekend I' ve studied also the inverse problem : given a hyperbola or at least 5 points find the foci and asymptotes. I've got a simple solution in the particular case that among these points there is a vertex . The solution is based on this nice theorem valid

RE: latitude with pegs and strings

Hello Arthur ! There is a simple and practical way to draw a hyperbola . I assume that these parameters are known: 2A = the constant difference between the distances of any point of the hyperbola from the two foci ; E = the eccentricity of the hyperbola ( 1 ). 1) Draw the two foci : two

RE: Astrolabe

The old book by W. Schroeder , Practical Astronomy , is a good reference. It has many pages devoted to the astrolabe theory and shows a graphic way to make an astrolabe. If you are familiar with math you'll find quite easy to translate the graphic instructions in trig formulae in order to

DIAL on the Moon

Sorry for the lapse : meridiana is the italian word for dial Alberto -- From: Nicelli Alberto Sent: venerdì 27 marzo 1998 16.40 To: 'sundial@rrz.uni-koeln.de' Subject: meridian on the Moon Dear dialists, yesterday a friend of mine asked me : can

meridian on the Moon

Dear dialists, yesterday a friend of mine asked me : can a meridian , built for a given latitude on Earth , be perfectly working somewhere on the Moon ? I like to share with you the answer to this nice question . After all Moon colonisation is in the near future and dialists will gain ground

RE: EoT calcula

Hi Jorge ! I've followed your hint to make a little program ( in MS FORTRAN) . In the file enclosed are the results of the EoT calculations with the formula I've sent you all. Values are calculated at Noon (Standard Time Central Meridian 15E). Errors always fall below 1 minute and in most

Again on the EoT formula

Thanks all for your answers ! The precise Equation of Time calculation is a rather serious matter, I'm aware ( Hi Jim! ). Nonetheless for didactic purpose and personal understanding I've found very useful to write down a closed formula , taking into account just in elementary way the obliquity

Equation of Time Formula

Hi all brothers dialists! Who knows the exact time and the exact ecliptic longitude of the earth's perihelion ? I need these values to calculate myself the Equation of Time with this formula I've obtained with a simple and traditional recipe : a little bit of spherical geometry and another

sundial software

I am a new entry in this interesting mailing list and I'm looking for a free or shareware sundial software able to calculate, if possible, also babylonian and italic hours. Do you know any Internet site to download it ? Thanks in advance ! Alberto Nicelli